The generation of hydrogen from natural gas via steam reforming is a well established commercial process. One drawback is that commercial units tend to be extremely large in volume and subject to significant amounts of methane slip, identified as methane feedstock which passes through the reformer un-reacted.
To reduce the size and increase conversion efficiency of the units, a process has been developed which uses calcium oxide to improve hydrogen yield by removing carbon dioxide generated in the reforming process. See U.S. patent application Ser. No. 10/271,406 entitled “HYDROGEN GENERATION APPARATUS AND METHOD”, filed Oct. 15, 2002, commonly assigned to the assignee of the present invention, the disclosure of which is incorporated herein by reference. The calcium oxide reacts with the CO2 in a separation reaction, producing a solid calcium carbonate (CaCO3) and absorbing the CO2.
The calcium carbonate reuse process requires that the calcium, in either CaCO3 or CaO (solid) be separated from the system gases, including the hydrogen gas product as well as carbon dioxide, un-reacted methane, excess oxygen and/or nitrogen, so the calcium carbonate particles can be either reformed to calcium oxide or transferred for reuse as calcium oxide. Cyclone separators are commercially known which can separate small particles from a fluid flow stream. At the 649° C. (1200° F.) to 983° C. (1800° F.) temperatures of the calcium carbonate reuse process, however, known commercial cyclone separators may not provide adequate resistance to thermal shock or a pressure drop meeting system requirements.